The present invention generally relates to fire protection systems for cold environments and, more specifically, for cold storage environments.
In fire protection sprinkler systems used in warehouse freezers and other cold storage environments, sprinkler piping system, which is typically connected to a water supply through a control valve and check valve, extends through a cold environment to sprinklers that are positioned in the freezer or cold storage environment to discharge extinguishant. The piping passing through the cold environment must contain a solution or a gas that will not freeze during normal set conditions. For large warehouse applications using early suppression fast response (ESFR) sprinklers, high piled storage can be protected using only ceiling mounted sprinklers. This means that in-rack sprinklers are not required at the various levels of rack storage areas to properly protect stored materials and the building from fire. Currently, preaction systems are limited to freezer systems using standard orifice type sprinklers at the ceiling and in-rack sprinklers in the adjacent rack storage areas.
Preaction sprinkler systems include a control or deluge valve, closed sprinklers, an air supervised piping system, and a detection system, which is electric or hydraulic/pneumatic. The detection system operates prior to the sprinkler operation in order to fill or pressurize the sprinkler piping system with water prior to operation of the sprinklers. With rapid operation of the detection system prior to sprinkler fused link operation, the piping system can fill with water prior to operation of the sprinklers. This allows the sprinkler system to be considered as a wet-pipe system, thus requiring less flow of sprinkler water after operation of system.
For ESFR applications it is important to have water or other extinguishing agents at the sprinklers before operation of the sprinklers from heat activated link of the sprinklers. Also current methods in application of ESFR sprinklers incorporate gridded-piping systems that allow water to be supplied to sprinklers in all locations at the ceiling from two directions. Also they are applied using wet-pipe technology that fills the complete system with antifreeze liquid that is premixed for the allowable low temperature of the environment, such as a freezer. In these systems when a single or multiple sprinklers operate, the amount of antifreeze discharged comes from the total system, piping network that can be very large. If a sprinkler is broken and no fire is present, the complete system is contaminated with plain water and must be drained immediately and replenished with proper antifreeze solution. If the antifreeze supply pump fails and a low pressure condition occurs the water supply can force its way into the antifreeze solution causing contamination resulting in freezing of the sprinkler piping systems. In a fire condition when water enters the system the complete piping system holding antifreeze is also contaminated and areas where water is not flowing are susceptible to freezing during a fire condition.